The long-term goal of this research is to Specifically, we plan to develop an exciting and captivating computer-based tobacco prevention program that uses contemporary computer game techniques delivered over a school-based intranet (i.e., networked computers linked to a school-based server). Since this is an ambitious goal, we are proposing a two-phase approach. Here, we propose to develop and examine the feasibility of this program. If we are successful, in a second phase, we will conduct a randomized trial to evaluate the long-term effectiveness of the program. Program components will target empirically supported mediating mechanisms derived from social cognitive theories and risk perception theory. These mediating mechanisms address the following educational objectives: (1) increasing negative and decreasing positive affect towards tobacco use, (2) changing cognitive aspects of attitudes, (3) decreasing subjective norms regarding tobacco use, (4) increasing perceived behavioral control, and (5) changing perceived risks of tobacco use (increasing the perceived risk of addiction, increasing perception of cumulative consequences, and decreasing optimism bias). The planned program consists of a minimum of 13 effective components delivered over eight sessions in 5th grade, a teacher's instructional guide to accompany the program and a series of newsletters that will be mailed to parents. Program components will be developed iteratively using formative qualitative evaluation and the effectiveness of each component will be evaluated quantitatively. We propose to conduct a feasibility study in two elementary schools to examine teacher and student satisfaction, program implementation and participation by students. The proposed computer-based program will be interactive and engaging, will minimize demands on teachers, will facilitate fidelity of implementation, and has the potential for tailoring. Intranet delivery of the program allows for feedback regarding aggregated classmates' tobacco use and attitude in an effort to change student's perception of normative use and attitude.